Leas U.S. Pat. Nos. 157,406 discloses a pump having a bellows type expansible chamber with the chambers being positioned radially about a central shaft member C. Mealey 1,109,349; Logan 2,146,123; and Kimsey 3,036,557 teach motors and pumps having radially disposed expansible chambers arranged about a common crankshaft so that a source of pressure fluid can be utilized to rotatably drive the main shaft. Miller 2,918,018 discloses a rotary pump having a shaft connected to one end of a plurality of bellows with the other end of the bellows being connected to a common support member such that the bellows are radially spaced about the shaft.
Other examples of known prior art: Cooper U.S. Pat. Nos. 184,461; Hibbard U.S. Pat. Nos. 938,146; Hyman U.S. Pat. Nos. 2,052,472; Rummel U.S. Pat. Nos. 2,122,352; Logan U.S. Pat. Nos. 2,146,123; Payne U.S. Pat. Nos. 2,830,544; Pigeroulet U.S. Pat. Nos. 3,267,861; Dikerson U.S. Pat. Nos. 3,730,054.
The employment of a bellows positioned within a cylinder and arranged to drive a crankshaft has heretofore been envisioned by others; however, there are many technical problems which have prevented the before mentioned motors from receiving proper acceptance in the market place. Primarily, the bellows are subjected to lateral movement along with reciprocatory movement and accordingly the uneven bending of one sidewall of the bellows respective to the other results in a short life thereof. Failure of the prior art bellows establishes communication between the expansible chamber and the crankcase thereby subjecting the crankcase to contamination of the power fluid.
In order to overcome this undesirable design feature various complicated mechanisms have been incorporated in an attempt to maintain the axial centerline of the bellows aligned with the axial centerline of the cylinder as evidenced by Kimsey U.S. Pat. Nos. 3,036,557 and Griswold 2,945,451; however, these complicated expedients are difficult to maintain and expensive to manufacture.
Accordingly, it would be desirable to provide an air motor having an expansible chamber formed between the bellows and a cylinder, with guide means being provided by which a connecting rod between the bellows and the crankshaft is maintained in exact axial alignment respective to the bellows and cylinders, and further that the guide means have associated therewith a seal means by which fluid contained within the crankcase is maintained properly separated from the power fluid which reciprocatingly drives the rod.